Shandong University of Science and Technology

The natural environment and public health are gravely threatened by the enrichment of soil potentially toxic elements (PTEs). To explore the contamination level, sources and human health risks posed by PTEs, high-density soil sampling was carried out in the upper Wei River region (UWRR). The results demonstrated that the pollution risk and ecological risk in UWRR as a whole were at a low level, but there were moderate or higher ecological risks of Hg and Cd in some areas. Source analysis of soil PTEs was conducted via absolute principal component score multiple linear regression (APCS-MLR) and positive matrix factorization (PMF) receptor models. APCS-MLR identified three potential sources, while the source division of PMF model was more detailed, which identified four potential sources: mining, coal combustion, machinery manufacturing and agricultural sources, with contribution percentages of 31%, 3%, 37% and 29% respectively. According to the probabilistic human health risk assessment (HHRA), the non-carcinogenic risk for adults was negligible, while that for children cannot be negligible. There were total carcinogenic risks for all populations, but the risk level was acceptable. The total cancer risk for children surpassed 1E-04 by 31.29%, implying a significant carcinogenic risk. Machinery manufacturing was found to be the most significant anthropogenic source of health concerns. This study offers an illustration of probabilistic risk assessment based on sources. The results of the study are favorable to provide new perspectives and scientific reference for soil PTE risk assessment and pollution control.

As a key component of composite materials, the interface quality is crucial for determining the mechanical properties of composites. Carbon fiber sizing treatment significantly enhances the fiber-matrix interface, a process extensively utilized in the carbon fiber industry. This study synthesized an environmentally friendly waterborne polyurethane sizing agent and investigated the impact of molecular weight, a critical factor, on composite performance by varying the soft segment type in the polyurethane. This research provides insights into cost-effective and eco-friendly surface treatment methods for carbon fibers and the design of robust interface structures.

We investigate the microscopic origin of the negative pressure produced by the constant energy density of the vacuum. It is shown that the zero-point photons in the quantum vacuum could generate the pressures of this type in confined spaces for the photon field. We find in particular that an anomalous radiation plays a role in the occurrence of a negative pressure from the quantum vacuum.

The catalysts of Ni nanoparticles supported on ZrO2, La2O3 and La2Zr2O7 were prepared and employed in photothermal catalytic DRM. High yield of H2 and CO (76.2 and 99.1 mmol g-1...

In the development of integrated circuits, operational amplifiers are indispensable basic units CMOS operational amplifiers are the core components in analog integrated circuits, which are widely used in signal acquisition, data processing, communications and other fields. components in analog integrated circuits, which are widely used in signal acquisition, data processing, communications and other fields, and their performance has a direct impact on the accuracy and stability of the entire system. With the continuous development of electronic technology, CMOS operational amplifiers play a vital role. operational amplifiers play a vital role in many fields. However, the misalignment problem has been one of the key factors affecting the performance of However, the misalignment problem has been one of the key factors affecting the performance of CMOS operational amplifiers. This paper introduces the basic principles of CMOS operational amplifiers, thoroughly studies the phenomenon of CMOS operational amplifiers' misalignment. This paper introduces the basic principles of CMOS operational amplifiers, thoroughly studies the phenomenon of CMOS operational amplifiers' misalignment, the definition and sources of the misalignment voltage and its effects, and analyzes the main reasons for its generation, including device mismatch, process deviation, and so on. In this paper, we summarize several methods to reduce distortion from dynamic distortion elimination technology and design and process optimization, which can effectively reduce the distortion voltage of CMOS op amps. The main dynamic misalignment elimination techniques are chopping and auto-zeroing, as well as a special form of auto-zeroing, i.e., correlation dual- sampling technique. Design and process optimization includes two methods of device selection and matching optimization and circuit topology design.

This paper is focused on vibration and acoustic analysis of functionally graded porous piezoelectric (FGPP) annular plate backed by cavity, which may be often encountered in marine and aerospace structures. Nonhomogeneous material and mechanical-acoustic-electric coupling lead to challenges for the vibro-acoustic modeling and analysis. Based on a modified variational principle, a semi-analytical method is developed for the FGPP annular plate-cavity with various boundary constrains. In order to naturally include the electric, acoustic and mechanical continuity at the boundaries and interfaces between adjacent subdomains, the Lagrange multiplier method is combined with least-square weighted residual method for both the plate and acoustic cavity. The fluid-structure coupling between the plate and cavity is incorporated by the work functions and velocity continuity at the interface. Expanding the response component analytically in the circumferential direction and numerically in the axial direction gives the semi-analytical solution and automatically identify each circumferential mode. A series of numerical results are compared with those from references and finite element (FEM) analysis to show excellent convergence, accuracy, and efficiency of the proposed method. It can be found that under the boundary conditions considered in this paper, Enlargement of the cavity length will firstly weaken the stiffness coupling between plate and cavity, and then reinforce the mass coupling between fluid and structure. For the forced vibro-acoustic responses, the most efficient mode is the n = 0 mode and dominate the acoustic responses. Since the mode is quite sensitive to the cavity length, one can optimize the length to strengthen or reduce sound radiation of the coupled system.

Post-processing of selective laser melted (SLMed) Ti6Al4V alloy with poor surface quality and low dimensional accuracy is a necessary operation to better achieve its operational performance. Considering the principle and advantages of ultrasonic vibration–assisted machining (UVAM) and textured tools, the synergistic application of UVAM and textured tools is expected to improve the micro-machining performance of SLMed Ti6Al4V alloy. The micro-machinability and machining mechanism of the SLMed Ti6Al4V alloy are investigated by a series of micro-machining with different scanning strategies, different ultrasonic vibration modes, different micro-texture tool types, and different elliptical trajectories. Multifaceted comparisons of machining results are presented in terms of cutting force, cutting temperature, equivalent stress and strain, temperature field, stress field, strain field, and chip formation. The machining results showed that the cutting forces of UVAM are reduced by 56.5 ~ 66.8% compared with conventional machining (CM). The differences in the cutting forces and temperatures of SLMed Ti6Al4V alloys with different scanning strategies are dependent on the microstructures and mechanical properties. The stress and strain fields are significantly affected by the coupled impact effect of cutting motion and ultrasonic vibration, and the UVAM processes improve serrated chip fracture properties. The dual effect of ultrasonic elliptical vibration and textured tools produces better machining performance, especially for the semi-elliptical micro-texture tools. The differences in machining response for different elliptical trajectories are attributed to the effects of tool vibration impact angle and the dynamic cutting thickness, and the machining response with a phase difference of φ = 45° is better.

Multiple active mining faces and extensive excavations under thick-hard strata in deep coal mines result in frequent strong mine earthquakes, often accompanied by significant surface subsidence deformation. Understanding the specific law of surface movement and the spatiotemporal distribution response to intense mine earthquakes is crucial for effectively preventing and mitigating dynamic disasters in deep mines. Utilizing the key layer theory, the intricate strata of the Yingpanhao Coal Mine are systematically delineated, drawing upon the engineering context of working faces 2201 and 2202 within the Ordos Chemical Co., Ltd., a subsidiary of the Shandong Energy Group. Field investigations are conducted to analyze the law of surface subsidence associated with multi-working face extraction within deep thick-hard strata, as well as to elucidate the spatiotemporal distribution characteristics of strong mine earthquakes. Furthermore, the interplay between law of surface subsidence and the spatial distribution of strong mine earthquakes is investigated, revealing a cohesive relationship between these phenomena. The research findings of this study provide certain references for the pre-control of surface subsidence and strong mine earthquakes during multiple working face and large space mining under thick-hard strata in deep coal mine with similar engineering geological conditions.

Spectral inversion, based on the odd-even decomposition principle of reflectivity, used the relationship between seismic data and wavelet amplitude spectrum to establish the inversion equation and achieve resolution-enhancement processing. Compared with deconvolution based on the L2 norm, the odd and even components of reflectivity using spectral inversion can weaken the tuning effect, identify thin layers, and obtain data with higher resolution. However, most post-stack seismic data are non-stationary, i.e., attenuation of amplitude, phase, and frequency with time exists. We derived a resolution-enhancement algorithm of non-stationary seismic data with quality factor Q based on the short-time Fourier transform. Due to the instability of the spectral inversion algorithm, the lateral continuity of the obtained result is poor. Therefore, we proposed a multichannel spectral inversion algorithm with lateral constraints. The algorithm inherits the high-resolution characteristics of spectral inversion and effectively enhances lateral continuity. Applications to model and field data sets show that the proposed L2 norm-based non-stationary multichannel spectral inversion method can be effectively applied to the resolution-improvement processing of non-stationary seismic data.

A comprehensive scientific analysis of temporal and spatial fluctuations of pollutants during the migration of groundwater is essential for precisely predicting their dispersion patterns and promoting rational regional development planning. In this research paper, a field radial dispersion test was conducted in decentralized drinking water sources downstream of the Fu Tuan River basin in Rizhao City, Shandong Province, China (FRSC). Chloride ion (Cl⁻) solution was utilized as a tracer for the experiment. The longitudinal dispersion coefficient (${a}_{L}$) was determined by standard curve matching and using straight-line graphical methods. Additionally, the impact of ${a}_{L}$ on pollutant transport was investigated by creating the MT3DMS solute transport model with the help of GMS 10.4 software. The results indicate that the ${a}_{L}$ of the submerged aquifer varies depending on the distance from the source well in the main runoff direction. At distances of 10 and 15 m, the values of ${a}_{L}$ were observed to be 0.56 m and 0.88 m, respectively. Moreover, when these observed values of ${a}_{L}$ are used as simulation parameters in solute transport modeling on the same space–time scale, the hydrodynamic dispersion effect exhibited by the well is found to be weaker than the actual hydrodynamic dispersion effect.

This paper researches the event-based stabilization of memristive neural networks (MNNs) via an integral-type trigger (ITT) scheme. Raising this issue is motivated by two factors: (1) a large number of event-trigger schemes overlook the historical state information, hence, it is conservative in terms of reducing triggering times; (2) the majority of existing Lyapunov functionals are positive definite and don’t have the memory period term. To address these issues, an ITT scheme which includes work interval and rest interval is introduced. In ITT scheme, a time-memory term is brought in the threshold function which can diminish the triggering times to preserve communication resources. Then, considering the characteristics of the ITT scheme and MNNs, an appointed-interval-dependent looped-function is constructed, which is positive definite solely at the sampling points and within the work interval, without necessitating this property in the rest interval. By using of inequality estimate technique and some lemmas, several stabilization criteria are established based on discrete Lyapunov and continuous Lyapunov methods. Finally, two examples suggest the effectiveness of the theoretical analysis and validity of the event-trigger scheme.